The Wall Street Journal had a report over the weekend highlighting a crucial aspect of the Syrian civil war: the mutual interest Assad and the Islamic State have had in squeezing out any somewhat reasonable opposition in the conflict:

The Islamic State, which metastasized from a group of militants seeking to overthrow the Syrian government into a marauding army gobbling up chunks of the Middle East, gained momentum early on from a calculated decision by Syrian President Basharal-Assad to go easy on it, according to people close to the regime.

Earlier in the three-year-old Syrian uprising, Mr. Assad decided to mostly avoid fighting the Islamic State to enable it to cannibalize the more secular rebel group supported by the West, the Free Syrian Army, said Izzat Shahbandar, an Assad ally and former Iraqi lawmaker who was Baghdad’s liaison to Damascus. The goal, he said, was to force the world to choose between the regime and extremists.

More:

“The Assad regime played a key role in ISIL’s rise,” said U.S. State Department spokeswoman Marie Harf at a news conference earlier this month. “They allowed for a security situation where ISIL could grow in strength. The Syrian regime fostered the growth of terrorist networks. They facilitated the flow of al Qaeda foreign fighters in . . . Iraq.”

At the outset of the revolution, the Assad regime released a bunch of terrorists, evidently in furtherance of this strategy:

Bassam Barabandi, a diplomat in Syria’s foreign ministry at the time who has since defected, offered a different explanation. “The fear of a continued, peaceful revolution is why these Islamists were released,” he said. “The reasoning behind the jihadists, for Assad and the regime, is that they are the alternative to the peaceful revolution. They are organized with the doctrine of jihad and the West is afraid of them.”

The Islamic State hates the Free Syrian Army as much as the government does, and has tried to crush it:

The Islamic State militants despised the FSA and its largely secular rebels, denouncing them as nonbelievers. By last summer, the Islamic State began grabbing territory the FSA had captured from the regime. In September, the Islamic State defeated the FSA’s Northern Storm Brigade in Azaz, a border outpost between Aleppo province and Turkey. The Islamic State quickly imposed its hard-line version of Islam, forbidding smoking, enforcing the segregation of the sexes and conservative dress.

Even as the Islamic State has grown in strength and the Syrian government has moved against it, the terror group has tacitly worked it to squeeze out the Free Syrian Army:

Still, at times its actions appeared to help the Syrian government in its fight against the FSA. Aleppo, Syria’s largest city, remained one of the few major strongholds of FSA resistance. Last month, the Islamic State quietly withdrew from the city’s northeastern suburbs, clearing the way for Syrian government forces to stream in. Not a shot was fired. The gains enabled government forces to flank FSA rebels from three sides in Aleppo.

In short, through its allergy to trying to support a force in Syria opposed to both the Islamic State and the regime, the Obama administration managed to settle on the one policy that both the terror group and Assad can agree on — namely, leaving the field to them.